US20090236682A1 - Layer stack including a tungsten layer - Google Patents
Layer stack including a tungsten layer Download PDFInfo
- Publication number
- US20090236682A1 US20090236682A1 US12/052,004 US5200408A US2009236682A1 US 20090236682 A1 US20090236682 A1 US 20090236682A1 US 5200408 A US5200408 A US 5200408A US 2009236682 A1 US2009236682 A1 US 2009236682A1
- Authority
- US
- United States
- Prior art keywords
- layer
- tungsten
- oxidation barrier
- barrier layer
- deposited
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 229910052721 tungsten Inorganic materials 0.000 title claims abstract description 134
- 239000010937 tungsten Substances 0.000 title claims abstract description 134
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 title claims abstract description 103
- 230000003647 oxidation Effects 0.000 claims abstract description 116
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 116
- 230000004888 barrier function Effects 0.000 claims abstract description 91
- 238000000151 deposition Methods 0.000 claims abstract description 44
- 238000004519 manufacturing process Methods 0.000 claims abstract description 15
- -1 tungsten nitride Chemical class 0.000 claims description 31
- 238000000034 method Methods 0.000 claims description 27
- 230000008021 deposition Effects 0.000 claims description 22
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 17
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 17
- 238000004544 sputter deposition Methods 0.000 claims description 14
- 238000004518 low pressure chemical vapour deposition Methods 0.000 claims description 11
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 claims description 5
- 150000003377 silicon compounds Chemical class 0.000 claims 1
- 150000003658 tungsten compounds Chemical class 0.000 claims 1
- 150000004767 nitrides Chemical class 0.000 description 15
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 15
- 239000003990 capacitor Substances 0.000 description 11
- 230000015572 biosynthetic process Effects 0.000 description 9
- 238000011065 in-situ storage Methods 0.000 description 8
- 238000003860 storage Methods 0.000 description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 7
- 238000011066 ex-situ storage Methods 0.000 description 7
- 239000001301 oxygen Substances 0.000 description 7
- 229910052760 oxygen Inorganic materials 0.000 description 7
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 238000010926 purge Methods 0.000 description 5
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000005530 etching Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000000137 annealing Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-AKLPVKDBSA-N silicon-31 atom Chemical compound [31Si] XUIMIQQOPSSXEZ-AKLPVKDBSA-N 0.000 description 1
- 230000008646 thermal stress Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/49—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET
- H01L29/4916—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET the conductor material next to the insulator being a silicon layer, e.g. polysilicon doped with boron, phosphorus or nitrogen
- H01L29/4925—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET the conductor material next to the insulator being a silicon layer, e.g. polysilicon doped with boron, phosphorus or nitrogen with a multiple layer structure, e.g. several silicon layers with different crystal structure or grain arrangement
- H01L29/4941—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET the conductor material next to the insulator being a silicon layer, e.g. polysilicon doped with boron, phosphorus or nitrogen with a multiple layer structure, e.g. several silicon layers with different crystal structure or grain arrangement with a barrier layer between the silicon and the metal or metal silicide upper layer, e.g. Silicide/TiN/Polysilicon
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/28—Manufacture of electrodes on semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/268
- H01L21/28008—Making conductor-insulator-semiconductor electrodes
- H01L21/28017—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon
- H01L21/28026—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon characterised by the conductor
- H01L21/28035—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon characterised by the conductor the final conductor layer next to the insulator being silicon, e.g. polysilicon, with or without impurities
- H01L21/28044—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon characterised by the conductor the final conductor layer next to the insulator being silicon, e.g. polysilicon, with or without impurities the conductor comprising at least another non-silicon conductive layer
- H01L21/28061—Making conductor-insulator-semiconductor electrodes the insulator being formed after the semiconductor body, the semiconductor being silicon characterised by the conductor the final conductor layer next to the insulator being silicon, e.g. polysilicon, with or without impurities the conductor comprising at least another non-silicon conductive layer the conductor comprising a metal or metal silicide formed by deposition, e.g. sputter deposition, i.e. without a silicidation reaction
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
- H01L21/76829—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
- H01L21/76832—Multiple layers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76801—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
- H01L21/76829—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
- H01L21/76834—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers formation of thin insulating films on the sidewalls or on top of conductors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/52—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
- H01L23/522—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
- H01L23/532—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body characterised by the materials
- H01L23/53204—Conductive materials
- H01L23/53209—Conductive materials based on metals, e.g. alloys, metal silicides
- H01L23/53257—Conductive materials based on metals, e.g. alloys, metal silicides the principal metal being a refractory metal
- H01L23/53266—Additional layers associated with refractory-metal layers, e.g. adhesion, barrier, cladding layers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/30—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells
- H10B12/48—Data lines or contacts therefor
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/30—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells
- H10B12/48—Data lines or contacts therefor
- H10B12/482—Bit lines
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B12/00—Dynamic random access memory [DRAM] devices
- H10B12/30—DRAM devices comprising one-transistor - one-capacitor [1T-1C] memory cells
- H10B12/48—Data lines or contacts therefor
- H10B12/488—Word lines
Definitions
- the present invention relates to a layer stack including a tungsten layer and to a method for producing a layer stack including a tungsten layer.
- tungsten In the production of tungsten metal gates the oxidation problem of tungsten is very critical. In the presence of oxygen, tungsten can oxidize and form whiskers or hillocks.
- the most critical production step is the cap nitride deposition, since it is the first high temperature process after the deposition and annealing of tungsten. If oxygen traces are present during this step, an extrusion of tungsten often can not be avoided. This can happen even at very low oxygen concentrations in the range of 10 parts per million and below. The resulting tungsten extrusions can be observed after the nitride deposition as bumps, hillocks or whiskers in the nitride layer. These nitride bumps are critical in later fabrication steps and therefore limit the fabrication yield.
- low temperature load-in can be carried out. Lowering the load-in temperature to 350° C. improves the morphology of the nitride surface.
- the relatively high temperature difference between the load in temperature and the deposition temperature causes high thermal stress, which is unfavorable.
- the low load-in temperature also provokes a contamination of the surface with particles.
- a second method for suppressing granularity of the nitride film is an in-situ reduction of the tungsten surface with an ammonia purge at around 600° C.
- the ammonia purge and the low temperature of the purge can, however, lead to a contamination of the tungsten surface with particles since the purge is still at critical temperature.
- an ammonia purge can lead to an incorporation of nitrogen into the tungsten which results in an unfavorable increase of resistance of the tungsten.
- Embodiments of the invention provide methods for producing a layer stack.
- One embodiment includes providing a tungsten layer, depositing an oxidation barrier layer that immunizes (i.e., protects) the tungsten layer against oxidation on top of the tungsten layer, and depositing a cap layer on top of the oxidation barrier layer.
- Embodiments of the invention further provide an integrated circuit including a tungsten layer, an oxidation barrier layer covering the tungsten layer, and a cap layer covering the oxidation barrier layer.
- FIG. 1 shows a schematic illustration of a first integrated circuit according to an embodiment of the present invention
- FIG. 2 shows a schematic illustration of a second integrated circuit according to an embodiment of the present invention
- FIG. 3 shows a schematic illustration of a third integrated circuit according to an embodiment of the present invention.
- FIG. 4 shows a schematic illustration of a fourth integrated circuit according to an embodiment of the present invention.
- FIG. 1 shows a schematic representation of a portion of an integrated circuit 10 according to one embodiment.
- the shown portion of the integrated circuit 10 comprises three visible layers 11 , 12 , 13 .
- the lowermost layer shown in FIG. 1 is a tungsten layer 11 .
- the tungsten layer 11 may for example serve as a gate layer in the integrated circuit 10 .
- the tungsten layer 11 may for example serve as a layer of wordlines in a memory device.
- the tungsten layer 11 may, however, also be another tungsten layer of the integrated circuit 10 .
- the tungsten layer 11 may be deposited by means of sputtering.
- the tungsten layer 11 may also be deposited by means of another deposition technique.
- the tungsten layer 11 may comprise a thickness of 100 nm.
- the tungsten layer 11 may also comprise a lower or higher thickness according to the specific needs of the application.
- layer 11 may also comprise another metal than tungsten that suffers from the oxidation problem.
- the tungsten layer 11 is covered by an oxidation barrier layer 12 of silicon nitride.
- the oxidation barrier layer 12 may also be composed of another kind of nitride.
- the oxidation barrier layer 12 is deposited using plasma enhanced chemical vapor deposition (PECVD) at a temperature below 450° C. according to one embodiment.
- the deposition temperature may for example be 400° C.
- the oxidation barrier layer 12 may also be deposited with another deposition technique that avoids oxidation of the tungsten layer 11 and the formation of whiskers and hillocks on the tungsten layer 11 .
- the oxidation barrier layer 12 may comprise a thickness between 10 nm and 30 nm according to one embodiment.
- the oxidation barrier layer 12 may for example comprise a thickness of 20 nm.
- the oxidation barrier layer 12 immunizes the subjacent tungsten layer 11 against oxidation. That is, the oxidation barrier layer 12 sufficiently mitigates or eliminates the formation of oxidation tungsten layer 11 under predetermined process conditions.
- the oxidation barrier layer 12 is covered by a cap layer 13 of silicon nitride according to one embodiment.
- the cap layer 13 may also be composed of another kind of nitride or of an oxide. Since the tungsten layer 11 is already immunized against oxidation by the oxidation barrier layer 12 , the cap layer 13 may be deposited at high temperature, even in the presence of oxygen traces.
- the cap layer 13 may for example be deposited in a low pressure chemical vapor deposition (LPCVD) furnace at a temperature above 650° C. according to one embodiment.
- the cap layer 13 may for example be deposited at a temperature of 780° C.
- the cap layer 13 may also be deposited by means of another deposition furnace.
- the cap layer 13 may comprise a thickness between 10 nm and 300 nm according to one embodiment.
- the cap layer 13 may for example comprise a thickness of 200 nm.
- the cap layer 13 may be used as a hard mask in a following etching process in the fabrication of the integrated circuit 10 .
- the deposition of the cap layer 13 may be performed at a higher deposition rate than the deposition of the oxidation barrier 12 .
- the portion of the integrated circuit 10 depicted in FIG. 1 may for example be part of a multilayered polymetal gate structure of the integrated circuit 10 .
- FIG. 2 shows a schematic representation of a portion of an integrated circuit 20 .
- the depicted portion of the integrated circuit 20 comprises three visible layers 21 , 22 , 23 .
- the lowermost layer of the depicted portion of the integrated circuit 20 is a tungsten layer 21 .
- the layer 21 may also be composed out of another metal than tungsten that suffers from the oxidation problem.
- the tungsten layer 21 may serve as a metal gate layer in the integrated circuit 20 .
- the tungsten layer 21 may for example be a wordline layer in the integrated circuit 20 .
- the tungsten layer 21 may also be any other tungsten layer of the integrated circuit 20 .
- the tungsten layer 21 may be deposited using a sputtering technique.
- the tungsten layer 21 may also be deposited using another deposition technique.
- the tungsten layer 21 may for example comprise a thickness of 100 nm according to one embodiment.
- the tungsten layer 21 may also comprise a lower or higher thickness.
- the tungsten layer 21 is covered with an oxidation barrier layer 22 composed out of tungsten nitride.
- the oxidation barrier layer 22 may be deposited on the tungsten layer 21 by means of sputtering.
- the oxidation barrier layer 22 may also be deposited by means of another deposition technique.
- the oxidation barrier layer 22 may be deposited in-situ or ex-situ.
- the oxidation barrier layer 22 may be deposited on the tungsten layer 21 in the same machine that was used for the deposition of the tungsten layer 21 .
- the oxidation barrier layer 22 may also be deposited in another machine than the one used for the deposition of the tungsten layer 21 .
- the oxidation barrier layer 22 may comprise a thickness between 3 nm and 20 nm according to one embodiment.
- the oxidation barrier layer 22 may for example comprise a thickness of 7 nm.
- the oxidation barrier layer 22 immunizes the tungsten layer 21 against oxidation.
- the oxidation barrier layer 22 is covered with a cap layer 23 of silicon nitride.
- the cap layer 23 may also be composed out of another nitride or an oxide.
- the cap layer 23 of the integrated circuit 20 may be deposited using a low-pressure chemical vapor deposition (LPCVD) furnace.
- the LPCVD furnace may for example be a vertical type LPCVD furnace.
- the cap layer 23 may also be deposited using another kind of furnace or by means of another deposition technique.
- the cap layer 23 may comprise a thickness between 10 nm and 300 nm according to one embodiment.
- the cap layer 23 may for example comprise a thickness of 220 nm.
- the cap layer 23 may be used as a hard mask in an etching process in a following processing step of the integrated circuit 20 .
- FIG. 3 depicts a schematic representation of a portion of an integrated circuit 30 .
- the depicted portion of the integrated circuit 13 comprises five visible layers 31 , 32 , 33 , 34 , 35 .
- the depicted portion of the integrated circuit 30 shows a schematic representation of a multilayered polymetal gate structure.
- the lowermost layer depicted in FIG. 3 is a layer 31 of polycrystalline silicon.
- the polycrystalline silicon layer 31 is covered by a layer 32 of tungsten nitride.
- the tungsten nitride layer 32 is covered by a layer 33 of tungsten.
- the tungsten nitride layer 32 is provided between the polycrystalline silicon layer 31 and the tungsten layer 33 as a barrier layer to suppress a silicidation reaction between the tungsten layer 33 and the polycrystalline silicon layer 31 .
- the tungsten nitride layer 32 may comprise a thickness between 3 and 15 nm according to one embodiment.
- the tungsten nitride layer 32 may for example comprise a thickness of 7 nm.
- the tungsten nitride layer 32 may be deposited on the layer of polycrystalline silicon 31 by means of sputtering.
- the tungsten nitride layer 32 may also be deposited by means of another deposition technique.
- the tungsten layer 33 may be deposited on the tungsten nitride layer 32 by means of sputtering.
- the tungsten layer 33 may be deposited on the tungsten nitride layer 32 in-situ or ex-situ.
- the tungsten layer 33 may comprise a thickness of 30 nm according to one embodiment.
- the tungsten layer 33 may also comprise a thickness of 100 nm, or any other thickness that is suitable for the application purposes of the integrated circuit 30 .
- an oxidation barrier layer 34 composed of tungsten nitride is deposited on top of the tungsten layer 33 .
- the oxidation barrier layer 34 is provided to prevent an oxidation of the tungsten layer 33 and to prevent the formation of whiskers and hillocks on the tungsten layer 33 .
- the oxidation barrier layer 34 may be deposited by means of sputtering. The deposition of the oxidation barrier layer 34 may be performed in-situ or ex-situ.
- the oxidation barrier layer 34 may also be deposited by means of another deposition technique.
- the oxidation barrier layer 34 may comprise a thickness between 3 nm and 20 nm according to one embodiment.
- the oxidation barrier layer 34 may for example comprise a thickness of 7 nm.
- the oxidation barrier layer 34 immunizes the tungsten layer 33 against oxidation.
- a cap layer 35 composed of silicon nitride covers the oxidation barrier layer 34 . Since the tungsten layer 33 is immunized against oxidation by the oxidation barrier layer 34 , the cap layer 35 may be deposited in a low pressure chemical vapor deposition furnace at a temperature above 650° C. even in the presence of small traces of oxygen. The cap layer 35 may for example be deposited at a temperature of 780° C. according to a particular embodiment. The cap layer 35 may also be composed of another nitride than silicon nitride or of an oxide. The cap layer 35 may comprise a thickness between 10 nm and 300 nm according to one embodiment. The cap layer 35 may serve as a hard mask in a later etching process during the fabrication of the integrated circuit 30 .
- the described oxidation barrier layers 12 , 22 , 34 can be provided between a metal layer and a cap layer in all situations in the fabrication of integrated circuits, when a metal layer has to be immunized against oxidation and formation of whiskers or hillocks before the cap layer is deposited in a furnace process.
- FIG. 4 depicts a schematic representation of a DRAM memory cell 40 .
- the DRAM memory cell 40 is capable of storing one bit of information.
- the DRAM memory cell 40 comprises a storage capacitor 48 .
- the storage capacitor 48 is provided to store an electric charge that represents the bit value of the DRAM cell 40 .
- the storage capacitor 48 may for example be a trench capacitor.
- the storage capacitor 48 may also be a stacked capacitor or any other kind of capacitor suitable for the fabrication of DRAM memory cells.
- the DRAM cell 40 also comprises a selection transistor 47 .
- the selection transistor 47 may be any kind of transistor suitable for the fabrication of DRAM cells.
- a gate contact of the selection transistor 47 is connected to a conductive wordline 56 .
- the selection transistor 47 can be switched on and off to connect the storage capacitor 48 to a conductive bitline 46 .
- the selection transistor 47 may be switched on and off by application of a suitable voltage to the wordline 56 . If the selection transistor is switched on, the charge stored on the storage capacitor 48 may be detected as a voltage on the bitline 46 . If the selection transistor 47 is switched on, the charge stored on the storage capacitor 48 may also be changed by applying a suitable voltage to the bitline 46 .
- the bitline 46 , the wordline 56 , and the storage capacitor 48 may for example be separated by an insulating oxide layer 49 .
- the wordline 56 depicted in FIG. 4 comprises a sequence of five visible layers 51 , 52 , 53 , 54 , 55 arranged atop of each other.
- the lowermost layer of the wordline 56 depicted in FIG. 4 is a layer 51 of polycrystalline silicon.
- the polycrystalline silicon layer 51 is covered by a layer 52 of tungsten nitride.
- the tungsten nitride layer 52 is covered by a layer 53 of tungsten.
- the tungsten nitride layer 52 is provided between the polycrystalline silicon layer 51 and the tungsten layer 53 as a barrier layer to suppress a silicidation reaction between the tungsten layer 53 and the polycrystalline silicon layer 51 .
- the tungsten nitride layer 52 may be deposited on the layer of polycrystalline silicon 51 by means of sputtering.
- the tungsten nitride layer 52 may also be deposited by means of another deposition technique.
- the tungsten layer 53 may be deposited on the tungsten nitride layer 52 by means of sputtering.
- the tungsten layer 53 may be deposited on the tungsten nitride layer 52 in-situ and ex-situ.
- the wordline 56 of the DRAM cell 40 depicted in FIG. 4 further comprises an oxidation barrier layer 54 deposited on top of the tungsten layer 53 .
- the oxidation barrier layer 54 is provided to prevent oxidation of the tungsten layer 53 and to prevent the formation of whiskers and hillocks on the tungsten layer 53 .
- the oxidation barrier layer 54 immunizes the tungsten layer 53 against oxidation.
- the oxidation barrier layer 54 may for example be composed of tungsten nitride. In this case the oxidation barrier layer 54 may be deposited by means of sputtering.
- the deposition of the oxidation barrier layer 54 may be performed in-situ or ex-situ.
- the oxidation barrier layer 54 may also be deposited by means of another deposition technique.
- the oxidation barrier layer 54 may also be composed of silicon nitride or of another kind of nitride.
- the oxidation barrier layer 54 may be deposited using PECVD at a temperature below 450° C. The deposition temperature may for example be 400° C.
- the oxidation barrier layer 54 may also be deposited with another deposition technique that avoids oxidation of the tungsten layer 53 and the formation of whiskers and hillocks on the tungsten layer 53 .
- a cap layer 55 composed of silicon nitride covers the oxidation barrier layer 54 . Since the tungsten layer 53 is immunized against oxidation by the oxidation barrier layer 54 , the cap layer 55 may be deposited in a LPCVD furnace at a temperature above 650° C. even in the presence of small traces of oxygen. The cap layer 55 may for example be deposited at a temperature of 750° C. The cap layer 55 may also be composed of another nitride than silicon nitride or of an oxide.
- the bitline 46 of the DRAM cell 40 shown in FIG. 4 comprises five visible layers 41 , 42 , 43 , 44 , 45 arranged atop of each other.
- the lowermost layer of the bitline 46 is a layer 41 of polycrystalline silicon.
- the polycrystalline silicon layer 41 is covered by a layer 42 of tungsten nitride.
- the tungsten nitride layer 42 is covered by a layer 43 of tungsten.
- the tungsten nitride layer 42 is provided between the polycrystalline silicon layer 41 and the tungsten layer 43 as a barrier layer to suppress a silicidation reaction between the tungsten layer 43 and the polycrystalline silicon layer 41 .
- the tungsten nitride layer 42 may be deposited on the layer of polycrystalline silicon 41 by means of sputtering.
- the tungsten nitride layer 42 may also be deposited by means of another deposition technique.
- the tungsten layer 43 may be deposited on the tungsten nitride layer 42 by means of sputtering.
- the tungsten nitride layer 43 may be deposited on the tungsten nitride layer 42 in-situ or ex-situ.
- An oxidation barrier layer 44 is deposited on top of the tungsten layer 43 of the bitline 46 of the DRAM cell 40 depicted in FIG. 4 .
- the oxidation barrier layer 44 is provided to prevent oxidation of the tungsten layer 43 and to prevent the formation of whiskers and hillocks on the tungsten layer 43 .
- the oxidation barrier layer 44 immunizes the tungsten layer 43 against oxidation.
- the oxidation barrier layer 44 may be composed of silicon nitride or of another kind of nitride.
- the oxidation barrier layer 44 may be deposited using PECVD at a temperature below 450° C. The deposition temperature may for example be 400° C.
- the oxidation barrier layer 44 may also be deposited with another deposition technique that avoids oxidation of the tungsten layer 43 and the formation of whiskers and hillocks on the tungsten layer 43 .
- the oxidation barrier layer 44 may also be composed of tungsten nitride.
- the oxidation barrier layer 44 may be deposited by means of sputtering. The sputtering of the oxidation barrier layer 44 may be performed in-situ or ex-situ.
- a cap layer 45 composed of silicon nitride covers the oxidation barrier layer 44 . Since the tungsten layer 43 is immunized against oxidation by the oxidation barrier layer 44 , the cap layer 45 may be deposited in a LPCVD furnace at a temperature above 650° C., even in the presence of small traces of oxygen. The cap layer 45 may for example be deposited at a temperature of 780° C. The cap layer 45 may also be composed of another nitride than silicon nitride or of an oxide. The cap layer 45 may serve as a hard mask in a later etch process during the fabrication of the DRAM cell 40 .
- bitline 46 and the wordline 56 of the DRAM cell 40 shown in FIG. 4 do not necessarily need to comprise the same sequence of layers.
Abstract
A method for producing a layer stack includes providing a tungsten layer, depositing an oxidation barrier layer that immunizes the tungsten layer against oxidation on top of the tungsten layer, and depositing a cap layer on top of the oxidation barrier layer. An integrated circuit is also described.
Description
- 1. Field of the Invention
- The present invention relates to a layer stack including a tungsten layer and to a method for producing a layer stack including a tungsten layer.
- 2. Description of the Related Art
- In the production of tungsten metal gates the oxidation problem of tungsten is very critical. In the presence of oxygen, tungsten can oxidize and form whiskers or hillocks. The most critical production step is the cap nitride deposition, since it is the first high temperature process after the deposition and annealing of tungsten. If oxygen traces are present during this step, an extrusion of tungsten often can not be avoided. This can happen even at very low oxygen concentrations in the range of 10 parts per million and below. The resulting tungsten extrusions can be observed after the nitride deposition as bumps, hillocks or whiskers in the nitride layer. These nitride bumps are critical in later fabrication steps and therefore limit the fabrication yield.
- In order to prevent oxidation of the tungsten surface, low temperature load-in can be carried out. Lowering the load-in temperature to 350° C. improves the morphology of the nitride surface. The relatively high temperature difference between the load in temperature and the deposition temperature, however, causes high thermal stress, which is unfavorable. The low load-in temperature also provokes a contamination of the surface with particles.
- A second method for suppressing granularity of the nitride film is an in-situ reduction of the tungsten surface with an ammonia purge at around 600° C. The ammonia purge and the low temperature of the purge can, however, lead to a contamination of the tungsten surface with particles since the purge is still at critical temperature. Furthermore, an ammonia purge can lead to an incorporation of nitrogen into the tungsten which results in an unfavorable increase of resistance of the tungsten.
- In summary, the outlined methods for suppressing granular growth of nitride films are not suitable for large scale production.
- Embodiments of the invention provide methods for producing a layer stack. One embodiment includes providing a tungsten layer, depositing an oxidation barrier layer that immunizes (i.e., protects) the tungsten layer against oxidation on top of the tungsten layer, and depositing a cap layer on top of the oxidation barrier layer.
- Embodiments of the invention further provide an integrated circuit including a tungsten layer, an oxidation barrier layer covering the tungsten layer, and a cap layer covering the oxidation barrier layer.
- So that the manner in which the above recited feature of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appending drawing. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of the scope, for the invention may admit to other equally effective embodiments.
-
FIG. 1 shows a schematic illustration of a first integrated circuit according to an embodiment of the present invention; -
FIG. 2 shows a schematic illustration of a second integrated circuit according to an embodiment of the present invention; -
FIG. 3 shows a schematic illustration of a third integrated circuit according to an embodiment of the present invention; -
FIG. 4 shows a schematic illustration of a fourth integrated circuit according to an embodiment of the present invention. -
FIG. 1 shows a schematic representation of a portion of an integratedcircuit 10 according to one embodiment. The shown portion of the integratedcircuit 10 comprises threevisible layers FIG. 1 is atungsten layer 11. Thetungsten layer 11 may for example serve as a gate layer in theintegrated circuit 10. Thetungsten layer 11 may for example serve as a layer of wordlines in a memory device. Thetungsten layer 11 may, however, also be another tungsten layer of the integratedcircuit 10. Thetungsten layer 11 may be deposited by means of sputtering. Thetungsten layer 11 may also be deposited by means of another deposition technique. Thetungsten layer 11 may comprise a thickness of 100 nm. Thetungsten layer 11 may also comprise a lower or higher thickness according to the specific needs of the application. In another embodiment,layer 11 may also comprise another metal than tungsten that suffers from the oxidation problem. - The
tungsten layer 11 is covered by anoxidation barrier layer 12 of silicon nitride. Theoxidation barrier layer 12 may also be composed of another kind of nitride. In order to avoid oxidation of the lower lyingtungsten layer 11 during the deposition of theoxidation barrier layer 12, theoxidation barrier layer 12 is deposited using plasma enhanced chemical vapor deposition (PECVD) at a temperature below 450° C. according to one embodiment. The deposition temperature may for example be 400° C. Theoxidation barrier layer 12 may also be deposited with another deposition technique that avoids oxidation of thetungsten layer 11 and the formation of whiskers and hillocks on thetungsten layer 11. Theoxidation barrier layer 12 may comprise a thickness between 10 nm and 30 nm according to one embodiment. Theoxidation barrier layer 12 may for example comprise a thickness of 20 nm. Theoxidation barrier layer 12 immunizes thesubjacent tungsten layer 11 against oxidation. That is, theoxidation barrier layer 12 sufficiently mitigates or eliminates the formation ofoxidation tungsten layer 11 under predetermined process conditions. - The
oxidation barrier layer 12 is covered by acap layer 13 of silicon nitride according to one embodiment. Thecap layer 13 may also be composed of another kind of nitride or of an oxide. Since thetungsten layer 11 is already immunized against oxidation by theoxidation barrier layer 12, thecap layer 13 may be deposited at high temperature, even in the presence of oxygen traces. Thecap layer 13 may for example be deposited in a low pressure chemical vapor deposition (LPCVD) furnace at a temperature above 650° C. according to one embodiment. Thecap layer 13 may for example be deposited at a temperature of 780° C. Thecap layer 13 may also be deposited by means of another deposition furnace. Thecap layer 13 may comprise a thickness between 10 nm and 300 nm according to one embodiment. Thecap layer 13 may for example comprise a thickness of 200 nm. Thecap layer 13 may be used as a hard mask in a following etching process in the fabrication of the integratedcircuit 10. - The deposition of the
cap layer 13 may be performed at a higher deposition rate than the deposition of theoxidation barrier 12. - The portion of the
integrated circuit 10 depicted inFIG. 1 may for example be part of a multilayered polymetal gate structure of the integratedcircuit 10. -
FIG. 2 shows a schematic representation of a portion of an integratedcircuit 20. The depicted portion of theintegrated circuit 20 comprises threevisible layers integrated circuit 20 is atungsten layer 21. Thelayer 21 may also be composed out of another metal than tungsten that suffers from the oxidation problem. Thetungsten layer 21 may serve as a metal gate layer in theintegrated circuit 20. Thetungsten layer 21 may for example be a wordline layer in theintegrated circuit 20. Thetungsten layer 21 may also be any other tungsten layer of theintegrated circuit 20. Thetungsten layer 21 may be deposited using a sputtering technique. Thetungsten layer 21 may also be deposited using another deposition technique. Thetungsten layer 21 may for example comprise a thickness of 100 nm according to one embodiment. Thetungsten layer 21 may also comprise a lower or higher thickness. - In order to avoid oxidation of the
tungsten layer 21 and a formation of whiskers and hillocks during the further processing of theintegrated circuit 20, thetungsten layer 21 is covered with anoxidation barrier layer 22 composed out of tungsten nitride. Theoxidation barrier layer 22 may be deposited on thetungsten layer 21 by means of sputtering. Theoxidation barrier layer 22 may also be deposited by means of another deposition technique. Theoxidation barrier layer 22 may be deposited in-situ or ex-situ. Theoxidation barrier layer 22 may be deposited on thetungsten layer 21 in the same machine that was used for the deposition of thetungsten layer 21. Theoxidation barrier layer 22 may also be deposited in another machine than the one used for the deposition of thetungsten layer 21. Theoxidation barrier layer 22 may comprise a thickness between 3 nm and 20 nm according to one embodiment. Theoxidation barrier layer 22 may for example comprise a thickness of 7 nm. Theoxidation barrier layer 22 immunizes thetungsten layer 21 against oxidation. - In the
integrated circuit 20 depicted inFIG. 2 , theoxidation barrier layer 22 is covered with acap layer 23 of silicon nitride. Thecap layer 23 may also be composed out of another nitride or an oxide. Thecap layer 23 of theintegrated circuit 20 may be deposited using a low-pressure chemical vapor deposition (LPCVD) furnace. The LPCVD furnace may for example be a vertical type LPCVD furnace. Thecap layer 23 may also be deposited using another kind of furnace or by means of another deposition technique. Thecap layer 23 may comprise a thickness between 10 nm and 300 nm according to one embodiment. Thecap layer 23 may for example comprise a thickness of 220 nm. Thecap layer 23 may be used as a hard mask in an etching process in a following processing step of theintegrated circuit 20. -
FIG. 3 depicts a schematic representation of a portion of anintegrated circuit 30. The depicted portion of theintegrated circuit 13 comprises fivevisible layers integrated circuit 30 shows a schematic representation of a multilayered polymetal gate structure. - The lowermost layer depicted in
FIG. 3 is alayer 31 of polycrystalline silicon. Thepolycrystalline silicon layer 31 is covered by alayer 32 of tungsten nitride. Thetungsten nitride layer 32 is covered by alayer 33 of tungsten. Thetungsten nitride layer 32 is provided between thepolycrystalline silicon layer 31 and thetungsten layer 33 as a barrier layer to suppress a silicidation reaction between thetungsten layer 33 and thepolycrystalline silicon layer 31. Thetungsten nitride layer 32 may comprise a thickness between 3 and 15 nm according to one embodiment. Thetungsten nitride layer 32 may for example comprise a thickness of 7 nm. Thetungsten nitride layer 32 may be deposited on the layer ofpolycrystalline silicon 31 by means of sputtering. Thetungsten nitride layer 32 may also be deposited by means of another deposition technique. - The
tungsten layer 33 may be deposited on thetungsten nitride layer 32 by means of sputtering. Thetungsten layer 33 may be deposited on thetungsten nitride layer 32 in-situ or ex-situ. Thetungsten layer 33 may comprise a thickness of 30 nm according to one embodiment. Thetungsten layer 33 may also comprise a thickness of 100 nm, or any other thickness that is suitable for the application purposes of theintegrated circuit 30. - In the
integrated circuit 30 depicted inFIG. 3 , anoxidation barrier layer 34 composed of tungsten nitride is deposited on top of thetungsten layer 33. Theoxidation barrier layer 34 is provided to prevent an oxidation of thetungsten layer 33 and to prevent the formation of whiskers and hillocks on thetungsten layer 33. Theoxidation barrier layer 34 may be deposited by means of sputtering. The deposition of theoxidation barrier layer 34 may be performed in-situ or ex-situ. Theoxidation barrier layer 34 may also be deposited by means of another deposition technique. Theoxidation barrier layer 34 may comprise a thickness between 3 nm and 20 nm according to one embodiment. Theoxidation barrier layer 34 may for example comprise a thickness of 7 nm. Theoxidation barrier layer 34 immunizes thetungsten layer 33 against oxidation. - In the
integrated circuit 30 depicted inFIG. 3 , acap layer 35 composed of silicon nitride covers theoxidation barrier layer 34. Since thetungsten layer 33 is immunized against oxidation by theoxidation barrier layer 34, thecap layer 35 may be deposited in a low pressure chemical vapor deposition furnace at a temperature above 650° C. even in the presence of small traces of oxygen. Thecap layer 35 may for example be deposited at a temperature of 780° C. according to a particular embodiment. Thecap layer 35 may also be composed of another nitride than silicon nitride or of an oxide. Thecap layer 35 may comprise a thickness between 10 nm and 300 nm according to one embodiment. Thecap layer 35 may serve as a hard mask in a later etching process during the fabrication of theintegrated circuit 30. - The described oxidation barrier layers 12, 22, 34 can be provided between a metal layer and a cap layer in all situations in the fabrication of integrated circuits, when a metal layer has to be immunized against oxidation and formation of whiskers or hillocks before the cap layer is deposited in a furnace process.
- The layer sequences described in the previous figures can for example be used to form wordlines and bitlines in a DRAM memory device.
FIG. 4 depicts a schematic representation of aDRAM memory cell 40. TheDRAM memory cell 40 is capable of storing one bit of information. TheDRAM memory cell 40 comprises astorage capacitor 48. Thestorage capacitor 48 is provided to store an electric charge that represents the bit value of theDRAM cell 40. Thestorage capacitor 48 may for example be a trench capacitor. Thestorage capacitor 48 may also be a stacked capacitor or any other kind of capacitor suitable for the fabrication of DRAM memory cells. - The
DRAM cell 40 also comprises aselection transistor 47. Theselection transistor 47 may be any kind of transistor suitable for the fabrication of DRAM cells. A gate contact of theselection transistor 47 is connected to aconductive wordline 56. Theselection transistor 47 can be switched on and off to connect thestorage capacitor 48 to aconductive bitline 46. Theselection transistor 47 may be switched on and off by application of a suitable voltage to thewordline 56. If the selection transistor is switched on, the charge stored on thestorage capacitor 48 may be detected as a voltage on thebitline 46. If theselection transistor 47 is switched on, the charge stored on thestorage capacitor 48 may also be changed by applying a suitable voltage to thebitline 46. Thebitline 46, thewordline 56, and thestorage capacitor 48 may for example be separated by an insulatingoxide layer 49. - The
wordline 56 depicted inFIG. 4 comprises a sequence of fivevisible layers wordline 56 depicted inFIG. 4 is alayer 51 of polycrystalline silicon. Thepolycrystalline silicon layer 51 is covered by alayer 52 of tungsten nitride. Thetungsten nitride layer 52 is covered by alayer 53 of tungsten. Thetungsten nitride layer 52 is provided between thepolycrystalline silicon layer 51 and thetungsten layer 53 as a barrier layer to suppress a silicidation reaction between thetungsten layer 53 and thepolycrystalline silicon layer 51. Thetungsten nitride layer 52 may be deposited on the layer ofpolycrystalline silicon 51 by means of sputtering. Thetungsten nitride layer 52 may also be deposited by means of another deposition technique. - The
tungsten layer 53 may be deposited on thetungsten nitride layer 52 by means of sputtering. Thetungsten layer 53 may be deposited on thetungsten nitride layer 52 in-situ and ex-situ. - The
wordline 56 of theDRAM cell 40 depicted inFIG. 4 further comprises anoxidation barrier layer 54 deposited on top of thetungsten layer 53. Theoxidation barrier layer 54 is provided to prevent oxidation of thetungsten layer 53 and to prevent the formation of whiskers and hillocks on thetungsten layer 53. Theoxidation barrier layer 54 immunizes thetungsten layer 53 against oxidation. Theoxidation barrier layer 54 may for example be composed of tungsten nitride. In this case theoxidation barrier layer 54 may be deposited by means of sputtering. The deposition of theoxidation barrier layer 54 may be performed in-situ or ex-situ. Theoxidation barrier layer 54 may also be deposited by means of another deposition technique. - The
oxidation barrier layer 54 may also be composed of silicon nitride or of another kind of nitride. In this case, in order to avoid oxidation of the lower lyingtungsten layer 53 during the deposition of theoxidation barrier layer 54, theoxidation barrier layer 54 may be deposited using PECVD at a temperature below 450° C. The deposition temperature may for example be 400° C. Theoxidation barrier layer 54 may also be deposited with another deposition technique that avoids oxidation of thetungsten layer 53 and the formation of whiskers and hillocks on thetungsten layer 53. - In the
wordline 56 of theDRAM cell 40 depicted inFIG. 4 , acap layer 55 composed of silicon nitride covers theoxidation barrier layer 54. Since thetungsten layer 53 is immunized against oxidation by theoxidation barrier layer 54, thecap layer 55 may be deposited in a LPCVD furnace at a temperature above 650° C. even in the presence of small traces of oxygen. Thecap layer 55 may for example be deposited at a temperature of 750° C. Thecap layer 55 may also be composed of another nitride than silicon nitride or of an oxide. - The
bitline 46 of theDRAM cell 40 shown inFIG. 4 comprises fivevisible layers bitline 46 is alayer 41 of polycrystalline silicon. Thepolycrystalline silicon layer 41 is covered by alayer 42 of tungsten nitride. Thetungsten nitride layer 42 is covered by alayer 43 of tungsten. Thetungsten nitride layer 42 is provided between thepolycrystalline silicon layer 41 and thetungsten layer 43 as a barrier layer to suppress a silicidation reaction between thetungsten layer 43 and thepolycrystalline silicon layer 41. Thetungsten nitride layer 42 may be deposited on the layer ofpolycrystalline silicon 41 by means of sputtering. Thetungsten nitride layer 42 may also be deposited by means of another deposition technique. - The
tungsten layer 43 may be deposited on thetungsten nitride layer 42 by means of sputtering. Thetungsten nitride layer 43 may be deposited on thetungsten nitride layer 42 in-situ or ex-situ. - An
oxidation barrier layer 44 is deposited on top of thetungsten layer 43 of thebitline 46 of theDRAM cell 40 depicted inFIG. 4 . Theoxidation barrier layer 44 is provided to prevent oxidation of thetungsten layer 43 and to prevent the formation of whiskers and hillocks on thetungsten layer 43. Theoxidation barrier layer 44 immunizes thetungsten layer 43 against oxidation. Theoxidation barrier layer 44 may be composed of silicon nitride or of another kind of nitride. In order to avoid oxidation of lower lyingtungsten layer 43 during the deposition of theoxidation barrier layer 44, theoxidation barrier layer 44 may be deposited using PECVD at a temperature below 450° C. The deposition temperature may for example be 400° C. Theoxidation barrier layer 44 may also be deposited with another deposition technique that avoids oxidation of thetungsten layer 43 and the formation of whiskers and hillocks on thetungsten layer 43. - The
oxidation barrier layer 44 may also be composed of tungsten nitride. In this case, theoxidation barrier layer 44 may be deposited by means of sputtering. The sputtering of theoxidation barrier layer 44 may be performed in-situ or ex-situ. - In the
bitline 46 of theDRAM cell 40 depicted inFIG. 4 , acap layer 45 composed of silicon nitride covers theoxidation barrier layer 44. Since thetungsten layer 43 is immunized against oxidation by theoxidation barrier layer 44, thecap layer 45 may be deposited in a LPCVD furnace at a temperature above 650° C., even in the presence of small traces of oxygen. Thecap layer 45 may for example be deposited at a temperature of 780° C. Thecap layer 45 may also be composed of another nitride than silicon nitride or of an oxide. Thecap layer 45 may serve as a hard mask in a later etch process during the fabrication of theDRAM cell 40. - The
bitline 46 and thewordline 56 of theDRAM cell 40 shown inFIG. 4 do not necessarily need to comprise the same sequence of layers. - While the foregoing is directed to embodiments of the present invention, other and further embodiments of the present invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims (26)
1. A method for producing a layer stack, comprising:
providing a tungsten layer;
depositing an oxidation barrier layer on top of the tungsten layer, wherein the oxidation barrier layer immunizes the tungsten layer against oxidation; and
depositing a cap layer on top of the oxidation barrier layer.
2. The method as claimed in claim 1 , wherein the oxidation barrier layer and the cap layer comprise a total thickness between 20 nm and 300 nm.
3. The method as claimed in claim 1 , wherein the cap layer is used as a hard mask in a following etch process or as etch stop liner.
4. The method as claimed in claim 1 , wherein the oxidation barrier layer comprises a tungsten compound.
5. The method as claimed in claim 4 , wherein the oxidation barrier layer comprises tungsten nitride.
6. The method as claimed in claim 1 , wherein the oxidation barrier layer comprises a thickness between 3 nm and 20 nm.
7. The method as claimed in claim 1 , wherein the oxidation barrier layer comprises a silicon compound.
8. The method as claimed in claim 7 , wherein the oxidation barrier layer comprises silicon nitride.
9. The method as claimed in claim 1 , wherein the oxidation barrier layer is deposited at a temperature below 450° C.
10. The method as claimed in claim 1 , wherein the oxidation barrier layer is deposited using plasma enhanced chemical vapor deposition.
11. The method as claimed in claim 1 , wherein the oxidation barrier layer comprises a thickness between 10 nm and 30 nm.
12. A method for producing a layer stack, comprising:
providing a tungsten gate electrode layer;
depositing an oxidation barrier layer of silicon nitride at a first temperature with a first deposition rate on top of the tungsten gate electrode layer; and
depositing a cap layer of silicon nitride at a second temperature with a second deposition rate on top of the oxidation barrier layer.
13. The method as claimed in claim 12 , wherein the first temperature is lower than the second temperature.
14. The method as claimed in claim 12 , wherein the first deposition rate is lower than the second deposition rate.
15. The method as claimed in claim 12 , wherein the cap layer is deposited at a temperature above 650° C., wherein the cap layer is deposited using low-pressure chemical vapor deposition.
16. A method for producing a layer stack, comprising:
providing a tungsten gate electrode layer;
depositing an oxidation barrier layer of tungsten nitride on top of the tungsten gate electrode layer; and
depositing a cap layer of silicon nitride on top of the oxidation barrier layer.
17. The method as claimed in claim 16 , wherein the cap layer is deposited at a temperature above 650° C., wherein the cap layer is deposited using low-pressure chemical vapor deposition.
18. The method as claimed in claim 16 , wherein the oxidation barrier layer is deposited using sputtering.
19. An integrated circuit, comprising:
a tungsten layer;
an oxidation barrier layer covering the tungsten layer; and
a cap layer covering the oxidation barrier layer.
20. The integrated circuit as claimed in claim 19 , wherein the tungsten layer is provided as a gate electrode layer.
21. The integrated circuit as claimed in claim 19 , wherein the cap layer comprises silicon nitride.
22. The integrated circuit as claimed in claim 19 , wherein the oxidation barrier layer and the cap layer comprise a total thickness between 20 nm and 300 nm.
23. The integrated circuit as claimed in claim 19 , wherein the oxidation barrier layer is a silicon nitride layer.
24. The integrated circuit as claimed in claim 19 , wherein the oxidation barrier layer comprises a thickness between 10 nm and 30 nm.
25. The integrated circuit as claimed in claim 19 , wherein the oxidation barrier layer is a tungsten nitride layer.
26. The integrated circuit as claimed in claim 19 , wherein the oxidation barrier layer comprises a thickness between 3 nm and 20 nm.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/052,004 US20090236682A1 (en) | 2008-03-20 | 2008-03-20 | Layer stack including a tungsten layer |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/052,004 US20090236682A1 (en) | 2008-03-20 | 2008-03-20 | Layer stack including a tungsten layer |
Publications (1)
Publication Number | Publication Date |
---|---|
US20090236682A1 true US20090236682A1 (en) | 2009-09-24 |
Family
ID=41088019
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/052,004 Abandoned US20090236682A1 (en) | 2008-03-20 | 2008-03-20 | Layer stack including a tungsten layer |
Country Status (1)
Country | Link |
---|---|
US (1) | US20090236682A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20130214415A1 (en) * | 2012-02-16 | 2013-08-22 | Sandisk Technologies Inc. | Metal Layer Air Gap Formation |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6797608B1 (en) * | 2000-06-05 | 2004-09-28 | Taiwan Semiconductor Manufacturing Company, Ltd. | Method of forming multilayer diffusion barrier for copper interconnections |
US20040188772A1 (en) * | 2003-03-28 | 2004-09-30 | Alain Blosse | Gate electrode for MOS transistors |
US20040238876A1 (en) * | 2003-05-29 | 2004-12-02 | Sunpil Youn | Semiconductor structure having low resistance and method of manufacturing same |
US20050205942A1 (en) * | 2004-03-19 | 2005-09-22 | Shian-Jyh Lin | Metal gate with composite film stack |
US20050218448A1 (en) * | 2004-03-18 | 2005-10-06 | Dae-Ik Kim | Transistor structure having an oxidation inhibition layer and method of forming the same |
US20060163677A1 (en) * | 2003-02-19 | 2006-07-27 | Samsung Electronic Co., Ltd. | Methods of forming a semiconductor device having a metal gate electrode and associated devices |
US20090111280A1 (en) * | 2004-02-26 | 2009-04-30 | Applied Materials, Inc. | Method for removing oxides |
-
2008
- 2008-03-20 US US12/052,004 patent/US20090236682A1/en not_active Abandoned
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6797608B1 (en) * | 2000-06-05 | 2004-09-28 | Taiwan Semiconductor Manufacturing Company, Ltd. | Method of forming multilayer diffusion barrier for copper interconnections |
US20060163677A1 (en) * | 2003-02-19 | 2006-07-27 | Samsung Electronic Co., Ltd. | Methods of forming a semiconductor device having a metal gate electrode and associated devices |
US20040188772A1 (en) * | 2003-03-28 | 2004-09-30 | Alain Blosse | Gate electrode for MOS transistors |
US20040238876A1 (en) * | 2003-05-29 | 2004-12-02 | Sunpil Youn | Semiconductor structure having low resistance and method of manufacturing same |
US20090111280A1 (en) * | 2004-02-26 | 2009-04-30 | Applied Materials, Inc. | Method for removing oxides |
US20050218448A1 (en) * | 2004-03-18 | 2005-10-06 | Dae-Ik Kim | Transistor structure having an oxidation inhibition layer and method of forming the same |
US20050205942A1 (en) * | 2004-03-19 | 2005-09-22 | Shian-Jyh Lin | Metal gate with composite film stack |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20130214415A1 (en) * | 2012-02-16 | 2013-08-22 | Sandisk Technologies Inc. | Metal Layer Air Gap Formation |
US9123714B2 (en) * | 2012-02-16 | 2015-09-01 | Sandisk Technologies Inc. | Metal layer air gap formation |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US10541252B2 (en) | Memory arrays, and methods of forming memory arrays | |
US6503791B2 (en) | Method of manufacturing semiconductor devices utilizing underlayer-dependency of deposition of capacitor electrode film, and semiconductor device | |
US9818756B2 (en) | Methods of forming a charge-retaining transistor having selectively-formed islands of charge-trapping material within a lateral recess | |
US20060033180A1 (en) | Low-density, high-resistivity titanium nitride layer for use as a contact for low-leakage dielectric layers and method of making | |
JP4524698B2 (en) | Semiconductor device having capacitive element and method of manufacturing the same | |
US10566280B2 (en) | Semiconductor device and method of manufacturing the same | |
US11923305B2 (en) | Methods of forming apparatuses having tungsten-containing structures | |
JP2005217407A (en) | Capacitor of semiconductor device, memory element including same, and method of fabricating same | |
TW201401442A (en) | Method of fabricating non-volatile memory device | |
JP2006210511A (en) | Semiconductor device | |
US20050142742A1 (en) | Semiconductor device and method of fabrication | |
US20030222296A1 (en) | Method of forming a capacitor using a high K dielectric material | |
US6133086A (en) | Fabrication method of a tantalum pentoxide dielectric layer for a DRAM capacitor | |
US6281066B1 (en) | Method of manufacturing a capacitor in a memory device | |
US20090236682A1 (en) | Layer stack including a tungsten layer | |
JP2015154028A (en) | Semiconductor device manufacturing method | |
WO2002073679A1 (en) | Vapor growth method for metal oxide dielectric film and pzt film | |
US20040166627A1 (en) | Methods for forming a capacitor on an integrated circuit device at reduced temperatures | |
JP4571836B2 (en) | Semiconductor device and manufacturing method thereof | |
US7531406B2 (en) | Method for fabricating an electrical component | |
US20060145233A1 (en) | Method of fabricating a semiconductor device capacitor having a dielectric barrier layer and a semiconductor device capacitor having the same | |
US8367550B2 (en) | Fabricating low contact resistance conductive layer in semiconductor device | |
JP2007311610A (en) | Semiconductor device, and its manufacturing method | |
US7148101B2 (en) | Capacitors of semiconductor devices and methods of fabricating the same | |
US20050013091A1 (en) | Multi-layer barrier allowing recovery anneal for ferroelectric capacitors |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: QIMONDA AG, GERMANY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BOUBEKEUR, HOCINE;KNOEFLER, ROMAN;SPERLICH, HANS-PETER;AND OTHERS;REEL/FRAME:021032/0554;SIGNING DATES FROM 20080506 TO 20080513 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |